Monday, February 04, 2008

Last week, we featured the debut marathon of Kayoko Fukushiof Japan.As the fastest Japenese woman ever over the HALF MARATHON, much was expected of Fukushi’s debut marathon in Osaka, but in the end, she left the world with memories of a different kind – 15 minutes to cover the final 2km, three falls in the final 300m in the finishing stadium, and testament to the challenges posed by the marathon distance.

In 1984, for the first time, women were allowed to run the marathon at the Olympic Games.The race was won by Joan Benoit, in a remarkable time of 2:24:52, beating off a stellar field including Weitz, Kristiansen, and Rosa Mota.The time was remarkable for a number of reasons.Not least of all, conditions in LA were hot and heavy – ahead of the Games, there was a great deal of anxiety over potential problems caused by the pollution – much as there are around the Beijing Olympic Games this year.

But in the end, the heat caused the problems, and the biggest problems of all were encountered by Gabriela Andersen-Scheiss, of Switzerland.

Andersen-Scheiss entered Olympic Games AND Physiology folklore thanks to her performance over the final 400m of the race.This video, shown below, is often shown at physiological conferences as a demonstration of what happens to the physiology when the body temperatures rises to reach a ‘critical threshold’.

What you will see in the video below (apologies for the poor quality – if anyone has a better version, let us know!), is that Andersen Scheiss enters the stadium clearly in distress, and over the next 400m, staggers around the track, taking an incredible 5 minutes to cover the final lap!The video edits out much of this last lap (again, let us know if you know where a better version exists), but you can get a good idea of just what is wrong – it seems as though the left side of her body is dragging the “paralysed” right hand side behind it.And this is typical of what happens when the core body temperature rises to above 40 degrees Celsius.

The role of the brain

We’ve brought this up before, but it bears repeating – until the mid to late-1980’s, the theory for exercise in the heat was that you fatigued because the body was unable to provide sufficient blood to the skin for cooling AND the muscles for exercise.In this theory, dehydration was a problem because it meant less blood, which only worsened the problem.But in 1979, Ethan Nadel found the first evidence that the blood flow was not the problem.This finding was repeated in numerous studies, where they found that the body was perfectly capable of getting enough blood to muscle and to skin.

However, the body temperature can still rise (this is a function of exercise intensity and the environment), and when it happens, the evidence began to suggest that the brain was involved. Why?Because scientists started to observe that when people in LABORATORIES hit a body temperature of 40 degrees, they started to display symptoms of neurological problems. Which is exactly what you see in Andersen-Scheiss – “paralysis” of one half of her body, inability to control the limbs, and so forth.This classic symptom was strongly suggestive of the neural contribution to fatigue.

It was later found that when the brain gets too hot, it actually recruits less muscle (Nybo and Nielsen, 2001).Of course, when you exercise in the heat, it’s not quite as simple as a brain the stops activating muscle when you get too hot – I (Ross) did a study in 2004 that found that the activation of muscle actually goes down BEFORE you get too hot.In other words, the brain slows you down by activating less muscle IN ADVANCE of hyperthermia, specifically so that you don’t reach this point of complete exhaustion and ‘paralysis’.

However, as the video above testifies, it happens, with dramatic consequences. Andersen-Scheiss, for her part, became something of an Olympic legend as a result of her courage.She ended up finishing in 37th place, some 20 minutes after Benoit.She was treated and released within 2 hours, showing how even the most intense effort is probably still within the reserve capacity for the body.

Jim Peters – the Vancouver 1954 marathon

J

im Peters of England was the Paula Radcliffe of his generation - he had broken the world record four times and was the first man to run under the 2:20 barrier, taking the record down by an astonishing eight minutes to 2:17:39!

So when he lined up in the 1954 Vancouver Empire State Games (today called the Commonwealth Games), he was the overwhelming favourite. This was the same Games, incidentally, that Roger Bannister and John Landy raced in what would later be called “the mile of the century”, with Bannister outkicking Landy to win.That race actually happed while this marathon was being run, and so Bannister actually sat in the stadium waiting for the men to finish.

Anyway, the marathon that day was particularly hot, and Jim Peters staggered into the stadium in first place, but was looking like he'd had too much to drink. He was swaying from side to side, and it looked as though one half of his body had been paralysed – much in the same way as Andersen-Scheiss would look 30 years later.

The conditions in Vancouver were pretty warm with starting temperatures in the shade in the high 20's Celsius. Reports were that the sun was so warm that the tar melted during the race!The temperatures may not jump out as being exceptionally high for those in the hotter parts of the world right now, but given that most of the athletes were not adapted to the heat, it was a tough day in the marathon.The conditions were so severe that out of 16 starters, only 6 finished the race.

Jim Peters was not one of them.After entering the stadium, with only 385 yards to run, Peters fell SIX TIMES within the first 200 yards.He took 11 minutes to cover that distance (making Fukushi look like a greyhound in her race!), before eventually collapsing for the final time – 200 yards SHORT of the finish line!He was taken to hospital, where he spent 7 hours being treated intensively before being released.

Incidentally, the athlete who was in second position with about two miles to run, Stan Cox, had also collapsed and ended up in hospital. At the 25 mile mark, he was so disoriented that he ran into a lamp-post, collapsing again.Eventually, police helped him to an ambulance, and he was taken to the hospital, where he’d later be joined by Peters.

And then finally, the eventual winner was a Scot, Joe McGee, who had actually collapsed five times on the course as well! But he heard that the two men who had been in front of him failed to finish, he picked himself up and went on to win! An attritional race if ever there was one!

The IronMan duel – Sian Welch and Wendy Ingram

And finally, for perhaps the most dramatic video we know of, we go to the IronMan Hawaii Triathlon of 1997, where Sian Welch and Wendy Ingram “race” over the final few hundred meters for fourth and fifth place.

This video, shown below, is difficult to watch, for the sheer agony that I’m sure most of you can relate to in some manner.It’s absolutely remarkable because it shows two elite athletes, both struggling with a combination of fatigue, muscle cramp and in the case of Welch in particular, hypoglycaemia.It’s quite clear that she’s in a disoriented state, and struggles to balance, find direction and stay co-ordinated.

Wendy Ingram, for her part, is cramping quite severely, and modifies her running style drastically in the final straight before the finish line.

What is most amazing, from a physiological point of view, is that the women move through different stages of what I would call “muscle activation patterns”.It’s as though there is a Plan A, which is to run absolutely normally, finishing strong (like some of the men who are finishing at around the same time as these two, you’ll see them in the background).

But given the difficulties both are experiencing, the brain quickly switches over the Plan B, which is this “modified running technique” – anything to keep going forward.Ingram’s “spider walk” is amazing, she’s clearly putting everything she has into what looks an incredibly uncomfortable running style!

Welch is unable to do even this – her muscles have simply been “switched off” and she has nothing left, mostly as a result of the low energy she has available and her fatigue – tired muscles with little fuel, and the brain says “No chance you’re running any more!”She’s unbalanced, uncoordinated and out of control.Eventually she staggers and walks to within meters of the finish line – she is on Plan C.But then she falls, taking Ingram down as well.And you’ll see in the video, the eventual winner between the two of them is the one who first realises the need for Plan D – Crawl!

So it’s an astonishing video, and you’ll hear reference to Julie Moss, a link you’ll find in the comments section of our Fukushi post from last week.

But this finish, and these two women, must surely go down as one of the bravest and most courageous, dramatic finishers in history!

Can you ever overcome the body’s limit through sheer willpower?

One question that is often asked when this whole area of “limits to performance” is discussed is this whole issue of “mind over matter”. What we are saying is that brain decides when “enough is enough”, and reduces the activation of muscle fibers BEFORE you even get near the dangerous levels of body temperature or fuel depletion, for example.

The logical question, however, is “Can an athlete, through sheer willpower, find that little bit extra, over-ride the brain’s protective reduction in muscle activation, and allow the athlete to go that little bit faster?”Professor Tim Noakes, who is one of the primary drivers of the theory of the brain protecting the body, often talks about the psychology and willpower aspects.And while they are relevant, I feel it’s not quite correct – it’s not simply a case that the guy who wants it most will win, which is unfortunately the spin that is often put on it.

So the answer is complex.Certainly, willpower and psychology play a role, and different people will tolerate different levels of discomfort.But I think that what these videos and stories show is that eventually, physiology wins the day.Peters, Welch, Andersen-Scheiss, and Ingram are all examples of athletes who have dug deep, found EVERYTHING their physiology has to offer, and quite literally run to the “edge of the limit”, but eventually, their physiology shuts down so completely that they simply could not run anymore.And yes, they survived.So in that sense, the brain did its job of protecting them, because all made recoveries, none “exercised themselves to death” (this happens, but it requires some special circumstances, we’ll discuss that in a future post).

So, to use a morbid analogy – no matter how badly you want to go, you cannot commit suicide by holding your breath – physiology wins.And similarly, during exercise, your willpower can take you that little bit closer to the limit.In fact, training takes you nearer that limit, since you learn what is tolerable and what is not.Motivation is of course important here too – given the right motivation, you might be prepared to tolerate a lot more than usual!But as you approach that “limit”, your body begins to progressively throw barrier after barrier in front of you.It becomes more and more difficult to hold the pace.Your brain is not activating muscle at the same level, and your perception of effort rises and rises.And eventually, physiology wins the day, and you stop, either voluntarily or because your legs fail to hold you up any more.This is human performance at the very extremes, but it’s still physiology!

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Comments:

Fascinating. Its definitely commendable that individuals can even reach the level where physiology is the only limitation.

What exactly is happening when you say a person is exhausted or muscles are fatigued ? In the case of hypoglycemia, it is clear that there is no fuel, no source of energy inside the body which can be tapped. In the case of high core temperature, once again it is somewhat clear what is happening inside the body, what is breaking down. But what exactly are you talking about when you say "fatigue" or exhaustion ?

Good question. The definition of "fatigue" lies at the heart of what is a controversy within the exercise sciences at the moment.

Let me elaborate:

Your explanation of "fatigue" with hypoglycemia is really interesting, because even when an athlete (or research subject in the lab, as the case may be) chooses to stop exercise or falls over with 'exhaustion', they still have some level of glycogen left. In otherwords, the body is not like a a car that runs out of fuel. The 'decision' to stop exercise, whether it's voluntary or simply forced on the athlete (like in the videos) happens even though there is still some reserve. Makes sense because the brain relies so much on glucose for energy that to run out completely would be fatal.

The same goes for heat. The evidence FROM THE LAB is that you voluntarily stop when your core temperature reaches 40 degrees (give or take a fraction here and there). Now, bodily harm and long term damage happens up above 41 degrees, so this is not harmful, and the volitional fatigue happens at a 'safe' point, though it does also come at a cost - see the video of Andersen-scheiss for evidence of that!

But let's answer your question - VOLITIONAL fatigue happens when the athlete CHOOSES to stop exercise. That happens, as I'm sure you can relate, when your perception of effort (how hard the exercise feels) exceeds what is acceptable to you.

So this is what I believe happens (and this is a whole body of research that is growing steadily):

The brain is taking into account all the incoming signals - how much energy you have, fuel use, body temperature, pH of the tissues, oxygen supply to the tissues, mechanical load on the joints etc.

The brain takes this input and generates a perception of effort - how you feel during exercise. As soon as that perception becomes unreasonably high, based on your motivation and the rewards, you make a decision to slow down, or to stop altogether. Obviously, motivation and reward are key here - if you're running for a PB or an Olympic medal your perception is different compared to if you're out for an easy run.

Key to this is that if you're doing a race or training session, you can choose to slow down. Often, scientists have done research in labs where they simply force athletes to run or cycle until they have to stop. But in the "REAL WORLD", you don't just have to stop - you have a choice to slow down long before that happens. So what likely happens then, is that your brain reduces the muscle activation so that you slow down. The result is that you don't ever get to that "limit". The decision to slow down is sometimes conscious, sometimes "subconscious", in that it's forced on you by the brain. But both are controlled through this perception of effort.

Now, the way you feel is the PHYSIOLOGICAL (this is key) manifestation of ALL The body's systems during exercise. Eventually, you reach the point where you body will no longer tolerate the perception, and you stop.

If you don't, then you may run to the point you see in these videos and stories, but you're still 'regulated' in that you can't run into death.

So that's it in a nutshell - it's a highly relevant and interesting topic and we are planning a MAJOR series on this whole concept of regulated fatigue in the future.

To add further to your point Dr Noakes writes in the Lore of Running that one purpose of interval training is to "reset" what the brain perceives as a safe limit to exercise. So a hard interval session that you had to abandon before is tolerable next time because your brain now knows that you survived it.

I have to say that I only PARTLY agree with the assertion over how training influences the brain. This is where I believe that Tim Noakes has pushed the wrong agenda very slightly. And I have to clarify - I did my PhD thesis under Tim's supervision. I now work in the department, directly underneath him, his door is three doors away from me, so we discuss this and other theories a great deal.

But to emphasize that the "brain adapts" is a very vague concept and I believe it misses the point a little.

Because look at each one in turn, starting with the heat issue:

When we train in the heat, and wear suits and do exercise in the hot condition, we're not "teaching the brain" how to cope with the heat, we're actually changing the physiology SO THAT THE SIGNALS TO THE BRAIN ARE CHANGED. In other words, with adaptation to the heat, the body increases the plasma volume, it increases the sweating response to lose more heat, it changes the distribution of blood flow to various parts of the body, perhaps becomes more economical so that heat production goes down, and so forth.

So the point is, much of the reason for heat adaptation happens to the signals, not the brain. Of course, the brain is still involved - I would not suggest that our psychology is not involved, but it gets too much emphasis. That aspect, the psychology and the "ability to tolerate" is pop-science, in my opinion. I cannot be proven (which is a big problem with advancing the research, incidentally - having done my PhD on this, we've almost reached a dead-end as far as proving it goes) and it over-simplifies the complex problem.

Same goes for interval training - when you do interval training, it's not as simple as just 'teaching the brain what it can tolerate'. That is part of it, yes, but think of what else is happening - your body response to training is so diverse and crucial, and that's a big part of why you adapt to training - your muscles, metabolism, fuel use, efficiency, etc. are all being trained too.

So in my opinion, the brain is involved, yes, but one has to look at the physiological adaptations as well, because they modify the inputs to the brain. So look at training as doing both - it changes the inputs, and then it changes how the brain interprets the inputs.

I have taken your advice about drinking when thirsty and taking electrolytes tablets only when craving salty foods. It has worked out well. I only used 8 for the 22 aid stations at Disney. Thanks.

I got injured in October during a 24 hour race completing 117 miles. My right quad atrophied and was 2.75cm smaller. In December, I started doing weights once a week and the strength has returned. The right quad is now just 2cm smaller than the left. I believe rapid strength gain is mostly neuromuscular in nature rather than from muscle growth. My limp is markedly reduced.

I have not returned to normal training. I have been doing a couple of miles a week at the track. However, I have been running races 1/2 marathons, 50 milers and marathons. My pace has steadily improved from 12:44/mi on Dec.1 to 8:25/mi in a marathon last Sunday. (My best marathon was in Oct. at a 7:50/mi pace).

Is the brain and the neuromuscular growth primarily responsible for the improvement? Does running a 9:09 pace at the Disney marathon help me run (activate muscles) for a 8:25 pace 3 weeks later at the Tallahassee marathon? Or did running one Yasso 800 at 3:12 at the track last Tuesday help create the pacing setpoint for the marathon? I was out of breath on the 800 so I know I am not as fit as pre-injury.

I am pleasantly surprised. I thought 4 months of detraining would take upwards to a year to recover from. For a veteran runner, is there a point to doing long slow runs? How many tempo runs do you need for brain training?

I understand the need for improving running economy. Overall fitness can be improved with low impact cross-training. I'm not sure anymore about putting in the miles. How much practice is really needed? for the brain?

I have a 100 mile race coming up on Mar. 1st. Will the brain training from the 117 mile run from last October help me run a good race?

Thanks for the comment and your experiences. Sorry to hear about your injury, but I must say, you've bounced back really quickly from it and seem to be running well again. Perhaps a bit of time on shorter distances will actually be a good thing in the long run.

If I can say one thing that hopefully puts to rest what actually is a bone of contention to me when it comes to this whole "Brain/governor" theory:

When you train, you train the physiology - this includes the muscles, the heart, the lungs, AND the brain. This concept of "brain training" is what has arisen out the "pop-science" that has sprouted up around this whole concept of regulated exercise.

I mean, what exactly is "Brain training"? I know that books have been written about it, very good ones, but to me, as a scientist, no one has really established what this means. What people are doing when they train is training their PHYSIOLOGY. And the brain is part of this, but then so is the liver, the muscles, the tendons, the heart, the blood vessels. All these factors are responsible for how you've improved in the last few weeks.

The point is, you don't train the brain independent of the rest of the body. So when an athlete goes out and trains in the heat, they're not teaching their brain how to tolerate the high temperature, they're teaching the PHYSIOLOGY how to keep the body temperature lower for longer and therefore the brain doesn't have to tolerate anything. Same thing for intervals, for long runs - you're training EVERYTHING, but the physiological systems, like muscle, heart, lungs, metabolism, that's what is important. You don't do "Brain training", you do "body training", and that happens to include the brain.

But what has developed is people have jumped on this theory, and I have to say that science hasn't exactly done much to dissuade this approach, and created this notion of focusing on the brain. The only way you can really do this is by thinking about your running, perhaps hypnosis. And that's a really poor substitute for long runs and speed work! So my advice is to keep training, keep focusing on the balance of all the elements of training.

And be aware of the role of perception and your mental approach to running, but it's not a conscious thing you train, in my opinion.

It sounds like the human body can adapt quicker than I thought. Each race I would ran is stimulating the physiological systems to run 30 seconds a mile faster (average) the following week.

I guess I am looking to find that optimal mix of training as my physiology adapts. What is the best use of a limited amount of time to train. Shouldn't the mix of training change once you peaked for a particular race? Wouldn't the repeated stimulus of repeated training workouts provide diminishing returns in terms of adaptation?

I will try to run this Sunday's marathon in Tampa in 3:30, 10 minutes faster than last Sunday. So, the 3x800m I ran yesterday isn't brain training but rather improves my physiological systems?

On a slight tangent, my left quad felt tight right above the knee, 18 miles into the last marathon. What causes the sensation of muscle tightness? Are the muscle fibers not relaxed when they should be? Is that mental fatigue -- I can usually have a fast kick at the end of the race when I am motivated. I am thinking about taking stretch breaks during my 100 miler if I think it will improve my overall time.

This is turning into an excellent debate, so thanks for those who have contributed so far.

Just to emphasize what Ross was saying. . .

Most scientists adopt a "reductionist" approach. By this I mean that they focus on one variable and reduce their conclusions to that one variable. For example, Joe Scientists hypothesizes that oxygen delivery causes fatigue. . .and so he spends a career performing studies that he hopes will demonstrate this. The result is that his lifework will show this, and effectively he has reduced the cause of fatigue to just that one thing.

Instead, as Ross has mentioned in the training example, we do not train only one organ at a time. In fact all of the organ systems are being trained simultaneously.

One problem is that when we are trained as scientists we are not normally taught about integration. Instead each part of the body/system is taught as a separate piece, and left that way.

Admittedly, it is difficult to perform integrated research. It often requires more (expensive) equipment and more expertise to interpret the data. At the same time it is relatively easy to operate as a reductionist, and also to publish as one since that was how most scientists are trained.---that is, the peer reviewers accept a reductionist's interpretation.

So again, as Ross said, all of our organs and systems operate together, not independently of each other, and so everything is indeed being trained at once.

The real challenge, and it really is a challenge, is to understand how all of these factors contribute in their own way. In other words, we must try to understand how these systems are integrated with each other.

Thought you might find this of interest, a guy in Australia doing irrepairable damage to himself in under an hour but in extreme heat. Considering the inbuilt survival systems of the body would this be a one off type situation?? Article to be found herehttp://books.google.com/books?id=gXxkYhqQCtIC&pg=PA61&lpg=PA61&dq=Mark+Dorrity+Wagga+1988&source=web&ots=9kTapoFvJp&sig=aR_LVvkLkfsw9fHf-MP1o26UK1UThanksAndrew T

Hi. I'm currently taking a limits physiology class as part of my Master's degree curriculum. I found your website trying to get clarification on something my professor said in class. I found this really helpful. Thanks.

Jonathan Dugas, PhDCurrent residence:Chicago, USAEmployment: Director of Clinical Development, The Vitality GroupResearch interests: Temperature regulation and exercise performance, with a special emphasis on how fluid ingestion affects those two things. In addition, the effects of exercise on health improvement and risk modification in large populationsSports interests: Cycling, running, triathlon, endurance sports

Full discolusre:The views expressed on this site are not those of the University of Cape Town (UCT), the Sports Science Institute of SA (SSISA), The Vitality Group, or Discovery Holdings.